Showing papers by "ETH Zurich published in 1985"
TL;DR: A preliminary energy refinement of the structure showed that the constraints derived from the n.m.r. data are compatible with a low energy spatial structure.
604 citations
TL;DR: An evaluation of the potential of nuclear magnetic resonance as a means of determining polypeptide conformation in solution is performed with the aid of a new distance geometry program which is capable of computing complete spatial structures for small proteins from n. m.m.r. data.
362 citations
TL;DR: Maximum-erasure burst-correcting codes over an alphabet of arbitrary size are constructed and shown to suffice for reconstructing the packets lost in "collisions" when these protocol sequences are used.
Abstract: A model is proposed for the situation where M users share a common communication resource but, because of unknown time offsets among their clocks, cannot transmit their data packets in a time-sharing mode and, because of the lack of a feedback link, can never determine these time offsets and also can never be sure of the outcomes of their individual packet transmissions. Each user is required to make his packet transmissions at times determined by a protocol signal that is independent of the data to be sent. The capacity and zero-error capacity regions of this channel are determined for both the unsynchronized and slot-synchronized cases; these four regions are shown to coincide. It is further shown that a dense set of rate points on the outer boundary of this region can be achieved in the slot-synchronized case. Specific constructions of protocol sequences for achieving these points are given, and the technique of "decimation decoding" is introduced for identifying the sender of each successfully transmitted packet. Maximum-erasure burst-correcting codes over an alphabet of arbitrary size are constructed and shown to suffice for reconstructing the packets lost in "collisions" when these protocol sequences are used.
361 citations
TL;DR: The structure of the biliprotein C-phycocyanin from the thermophilic cyanobacterium Mastigocladus laminosus has been determined at 3 A resolution by X-ray diffraction methods and the electron density map could be improved by solvent flattening and has been interpreted in terms of the amino acid sequence.
335 citations
TL;DR: A more complete characterization of the 1H spin systems prior to the step of sequential resonance assignments was achieved with the presently introduced methodology than was possible in earlier studies of proteins of similar size.
Abstract: Novel strategies for elucidation and classification of amino acid 1H-NMR spin systems in proteins were developed exploiting recently introduced two-dimensional NMR techniques such as phase-sensitive double-quantum-filtered correlated spectroscopy, relayed coherence transfer spectroscopy, double quantum spectroscopy and nuclear Overhauser spectroscopy. Due to the improved resolution in phase-sensitive spectra, the fine structure of cross peaks could be exploited as a powerful source of information for establishing 1H-1H connectivities. Principles for the interpretation of multiplet structures of absorption mode cross peaks are discussed. With these methods the 1H spin systems of rabbit liver metallothionein-2 were elucidated and classified according to amino acid types. Despite the intrinsically difficult situation arising from the unusual amino acid composition of this protein, a more complete characterization of the 1H spin systems prior to the step of sequential resonance assignments was achieved with the presently introduced methodology than was possible in earlier studies of proteins of similar size.
276 citations
TL;DR: In a randomised, multicentre study intravenous IgG was compared with oral corticosteroids in 108 children with untreated acute immune thrombocytopenic purpura, and rapid responders had a smaller mean initial platelet-associated IgG index which returned more rapidly and more permanently to normal than that of slow responders.
250 citations
TL;DR: In this article, the authors analyzed the spin diffusion in resolved solid-state NMR spectra for various types of systems, including dipolar coupled spin-(1/2) systems in the presence of extraneous spins, and systems of quadrupolar spins with and without an additional dipolar reservoir.
Abstract: Spectral spin diffusion in resolved solid-state NMR spectra is analyzed for various types of systems, including dipolar coupled spin-(1/2) systems in the presence of extraneous spins, and systems of quadrupolar spins with and without an additional dipolar reservoir. Diffusion of Zeeman and quadrupolar order via single-quantum and double-quantum spin-diffusion mechanisms is considered. Special attention is paid to the frequency offset dependence of the spin-diffusion rate. The theoretical predictions are verified by spin-diffusion measurements using two-dimensional spectroscopy techniques for $^{13}\mathrm{C}$ deuterium, and $^{14}\mathrm{N}$ resonance in single crystals.
237 citations
TL;DR: The subcellular distribution of the type II enzyme of cAMP-dependent protein kinase (cAMP-dPK II) in epithelial and fibroblastic cells was determined by indirect immunofluorescence microscopy and was associated with microtubule-organizing centers and mitotic spindle poles.
223 citations
TL;DR: In this paper, complete sequence-specific 1H nuclear magnetic resonance assignments for the backbone hydrogen atoms in Tendamistat, a protein with 74 residues, were obtained from NOESY observation of 1H-1H short distance constraints, measurements of the spin-spin couplings 3JHNα and a qualitative identification of slowly exchanging amide protons.
196 citations
TL;DR: In this paper, the search for the decay μ+ → e+e+e−e− with the SINDRUM spectrometer has been continued and a new upper limit for the branching ratio B μ→3 e = Γ(μ→ 3 e ) Γ (μ→ e 2ν) −12 (90% CL ) was given.
166 citations
TL;DR: In this article, the unusual properties of CeSb are reviewed and new results presented, in particular the magnetic phase diagram has been investigated under high magnetic fields where a new phase FP′ (+++0) has been discovered and under high pressure which increases strongly TN (TN = 30.5 K at P = 21 kbar), changes the ordering to type I and suppresses the non-magnetic planes.
TL;DR: In this article, it is suggested that the fragmentation of the exciter is due to a fragmentation of a primary energy release, and that the spikes thus originate close to or in the energy release region.
Abstract: Decimetric radio events with large numbers of spikes during the impulsive phase of flares have been selected. In the observing range of 100 to 1000 MHz some flares have of the order of 10000 spikes or more. The average half-power bandwidth of spikes has been measured to be only 1.5% of the spike frequency. Since the emission frequency is determined by some source parameter (such as plasma frequency or gyrofrequency) the source dimension must be a small fraction of the scale length. From the flare configuration a typical upper limit of the dimension of 200 km is found. The observed fragmentation in the radio emission cannot be explained by a patchy emission mechanism of a single and much larger source without an additional (and unknown) assumption. It is proposed that the fragmentation already occurs in the exciter. Four events were analyzed in detail and compared to UV, SXR, and HXR data. The density of the loops where the SXR and HXR emission was observed has been measured before the flare. The plasma frequency well agrees with the observed frequency of spikes. The spikes thus originate close to or in the energy release region. It is suggested here that the fragmentation of the exciter is due to a fragmentation of the primary energy release. Each of these 104 ‘microflares’ would release an energy of the order of 1026 erg within 0.05 s.
TL;DR: The authors found a sharp negative carbon-isotope shift in the carbonate of a clay immediately above a marker in the Precambrian/Cambrian boundary, the China C marker, and interpreted this signal as evidence of sudden decrease in fertility before the Cambrian explosion of invertebrate evolution.
Abstract: The Palaeozoic and Mesozoic eras were terminated by faunal changes involving mass extinction of the old and explosive evolution of the new fauna, but the fossil record shows only a Cambrian Explosion at the end of the Precambrian. Stanley speculated that the explosion was only possible after the ubiquitous algae community had been largely eliminated1; ecological niches were thus liberated for explosive evolution. If the Cambrian Explosion were preceded by a mass mortality (or by a mass extinction), such an event should leave a record in the form of geochemical anomalies. We have undertaken a search for geochemical anomalies at the Precambrian/Cambrian contact. We report here the discovery of a sharp negative carbon-isotope shift in the carbonate of a clay immediately above a marker in the Precambrian/Cambrian boundary, the China C marker, and interpret this signal as evidence of sudden decrease in fertility before the Cambrian explosion of invertebrate evolution. The discovery suggests that the Precambrian/Cambrian boundary might be defined by an event-marker at a palaeontologically correlative horizon.
TL;DR: In this paper, an optimization procedure is described for NMR techniques that require signal averaging of expts. with a variable time delay, either for the suppression of artifacts or for the optimization of coherence transfer over a given frequency range.
TL;DR: A derivative of the kanamycin-resistance (KmR) transposon Tn5 was constructed (Tn5-751) that carried the trimethoprim-Resistance (TpR) determinant from plasmid R751 as an additional marker and the arc genes were tightly clustered, confirming earlier genetic evidence.
TL;DR: A flow-through process for the mineralization of dichloromethane was developed in this paper, where the authors compared the growth properties of ten isolates in batch and continuous culture and found that the maximum growth rate decreased with an increase in substrate concentration.
TL;DR: It appears that the BChl‐protein complex (chlorosome subunit, 5.2 × 6 nm) composed of 12 5.6 kDa polypeptides corresponds to the 'globular units' found by electron microscopy within the chlorosomes.
TL;DR: It is demonstrated that UCu5 undergoes another phase transition around 1 K which is, so far, of unknown origin but, more important, in- volves the heavy-mass quasiparticles that lead to the low-temperature enhanced specific heat.
Abstract: The formation of a heavy-electron state in a magnetically ordered material is established by measurements of the low-temperature specific heat of U${\mathrm{Cu}}_{5}$ and UAg${\mathrm{Cu}}_{4}$. In U${\mathrm{Cu}}_{5}$ this state undergoes a continuous but hysteretic phase transition which removes parts of the Fermi surface with a high density of electronic states and leads to a resistivity increase of almost an order of magnitude.
TL;DR: In this article, the electrical resistivity of annealed polycrystalline CeCu6 was measured between 0.04 and 1 K and the specific heat was reported to be linear in T above 0.6 K.
TL;DR: A keyboard concept based on biomechanical considerations was studied with 51 trained typists and it was found that less pain and an increased feeling of relaxation were reported by the subjects when operating the split keyboards.
Abstract: A keyboard concept based on biomechanical considerations was studied with 51 trained typists. The keyboard is split into two half-keyboards. An adjustable model allowed study of the preferred settings of opening angles, lateral inclinations, and distances of the split keyboard. The preferred split keyboards decrease the lateral deviation of the hands, and the use of a large forearm-wrist support is associated with a backwards leaning of the subjects and with an increased pressure of forearm-wrists onto the support. After the typing tasks, about two-thirds of the subjects asserted that they preferred the split keyboard models. Less pain and an increased feeling of relaxation were reported by the subjects when operating the split keyboards.
TL;DR: In this article, two types of headspace traps are presented and tested, both showing the dimensions of a piece of capillary column, both of which contain charcoal particles melted into the glass surface and extremely thick (12-15 μm) coatings of stationary phase.
TL;DR: In this article, the fabrication and optical properties of reactive ion-etched, totally reflecting mirrors for single-mode GaAs rib waveguides are described, in order to increase packing density and to facilitate waveguide to fiber coupling.
Abstract: The fabrication and optical properties of reactive ion-etched, totally reflecting mirrors for single-mode GaAs rib waveguides are described. Low loss and orientation independance make the device useful in integrated optics, in order to increase packing density and to facilitate waveguide to fiber coupling. Results of displacement sensitivity calculations are also shown.
TL;DR: The results are compared with previous anatomical investigations and confirm the electrophysiologically demonstrated FEF-PPRF-abducens disynaptic pathway.
TL;DR: In this article, the vibrational spectra of chlorodifluoromethane (Freon 22) were measured at intermediate and high resolutions between 800 and 12 000 cm-1 by interferometric (FTIR) techniques.
Abstract: The vibrational spectra of chlorodifluoromethane (Freon 22) have been measured at intermediate and high resolutions between 800 and 12 000 cm-1 by interferometric (FTIR) techniques. The CH overtone spectra exhibit a pronounced multiple-resonance structure which can be understood in terms of the ‘universal’ anharmonic CH stretching-bending hamiltonian. Quantitative predictions from this hamiltonian agree well (without adjustments) with previous experimental data on the visible spectra, which could not be correctly assigned before.
TL;DR: An exact expression for the overall rotation generated by two or three consecutive noncommuting rotations is used for the analysis of several known composite pulse sequences and recursive expansion procedures in this paper, and analytical expressions for the dependence of spin inversion on radiofrequency field strength are given.
TL;DR: In this article, a measurement of the production of muon pairs in 194 GeV/c π−tungsten interactions is presented, where a sample of 155,000 events with mass higher than 4.07 GeV /c2 has been used to determine the differential cross-section as a function of the scaling variables.
Abstract: We present a measurement of the production of muon pairs in 194 GeV/c π−-tungsten interactions. A sample of 155,000 events with mass higher than 4.07 GeV/c2 has been used to determine the differential cross-section as a function of the scaling variables\(\sqrt \tau \) andxF.
TL;DR: In this article, some mono-and disubstituted ethenes have been asymmetrically hydroformylated with rhodium and platinum catalysts using (2 S,3 S )-2,3-bis(diphenylphosphino)butane (Chiraphos) as the chiral ligand (maximum optical yield ∼ 45%).
TL;DR: In this article, the steric course of the diastereoselective addition of the 1-bromomagnesium derivative 2 of N -pivaloyl-tetrahydroisoquinoline (THIQ) to acetophenone was proved by X-ray crystal structure analysis.
TL;DR: Hemoglobin encapsulated in liposomes made from negatively charged phospholipids is less stable than hemoglobin entrapped in isoelectric phosphatidylcholine, and the instability of hemoglobin is due to the protein interacting with the negatively charged lipid bilayer.
Abstract: Hemoglobin is encapsulated in liposomes of different lipid composition. The resulting dispersion consists primarily of multilamellar liposomes (hemosomes) of a wide particle size distribution (diameter ranging mainly between 0.1 and 1 micron). The encapsulation efficiency is significantly larger with liposomes containing negatively charged lipids as compared to liposomes made of phosphatidylcholine. The integrity of the phospholipid bilayer is maintained in the presence of hemoglobin. The reaction rate of CO binding to encapsulated hemoglobin is reduced compared to that of free hemoglobin, but it is still greater than that observed in red blood cells. Hemoglobin encapsulated in liposomes made from negatively charged phospholipids is less stable than hemoglobin entrapped in isoelectric phosphatidylcholine. The instability of hemoglobin is due to the protein interacting with the negatively charged lipid bilayer. This interaction leads in turn to hemoglobin denaturation, possibly involving the dissociation of the heme group from the heme-globin complex. The nature of the negatively charged phospholipid is important in promoting the interaction with hemoglobin, the effect being in the order phosphatidic acid greater than phosphatidylinositol congruent to phosphatidylglycerol greater than phosphatidylserine. The presence of equimolar amounts of cholesterol in the phospholipid bilayer has a stabilizing effect on hemoglobin. This effect is pronounced with saturated phospholipids, but it is also observed, though to a lesser extent, with unsaturated ones, indicating that the bilayer fluidity has a modulating effect. The presence of cholesterol possibly interferes with secondary interactions following the binding of hemoglobin to the negatively charged lipid bilayer.
TL;DR: Strong DNA homology was found between the Streptomyces antibioticus and the S. glaucescens tyrosinase structural genes and both genes showed a similar regulation when introduced into melanin-negative hosts.
Abstract: The gene from Streptomyces glaucescens coding for an inducible tyrosinase was cloned using the low copy vector pIJ41 and the melanin-negative strain Streptomyces lividans TK23 as host. Hybridisation experiments as well as complementation studies showed that melC mutant strains carry large deletions of more than 10.5 kb, comprising the structural gene for tyrosinase, while melA and melB strains carry mutations in genes involved in the expression of tyrosinase activity. Strong DNA homology was found between the Streptomyces antibioticus and the S. glaucescens tyrosinase structural genes and both genes showed a similar regulation when introduced into melanin-negative hosts. While both tyrosinases exhibited clear induction in S. glaucescens, constitutive expression was observed in S. lividans. Northern blot experiments showed that tyrosinase expression is regulated at the transcriptional level and that the gene (822 bp) is part of a 2.3 kb transcript. The main start of the mRNA at about 475 bp upstream from the tyrosinase N-terminus was located by S1-mapping experiments.